This Phase II project involves development and pre-clinical qualification of a left ventricular assist system (LVAS) that features a miniature axial flow blood pump with simplified (e.g., blood-immersed) bearings. In Phase I convincing evidence was obtained demonstrating the feasibility of this new axial flow pump. In particular the results of several in vivo tests, including one of 2-months duration and one ongoing experiment approaching 5 months, indicate the pump's potential to operate in blood for periods of time consistent with clinical bridge-to-transplant (BTT) applications. Now in Phase II the goals are to complete development of this LVAS and conduct sufficient in vitro and animal testing to document its overall safety and performance, in anticipation of a clinical trial for BTT applications lasting up to 90 days. In addition to the pump, the LVAS consists of inflow/outflow cannulae and externally worn components, e.g., primary battery, back-up battery, and pump controller, which provide power and closed-loop speed control of the implanted pump. A small diameter percutaneous wire connects the implanted pump to the external controller. If ultimately successful, this new LVAS would be vastly simpler, smaller, and less costly than the products available today for clinical use. PROPOSED COMMERCIAL APPLICATION: The bridge-to-transplant application would only be the first use of this type of LVAS to treat heart failure patients. Beyond bridge-to-transplant applications, the LVAS would then be qualIfied for use as an alternative-to-transplant. This latter application has a very large commercial potential and is the most significant for this device.